/*
 * pgp-mpi.c
 *      OpenPGP MPI helper functions.
 *
 * Copyright (c) 2005 Marko Kreen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This source code file contains modifications made by THL A29 Limited ("Tencent Modifications").
 * All Tencent Modifications are Copyright (C) 2023 THL A29 Limited.
 * 
 * contrib/pgcrypto/pgp-mpi.c
 */
#include "postgres.h"

#include "contrib/pgcrypto/px.h"
#include "contrib/pgcrypto/pgp.h"

int
pgp_mpi_alloc(int bits, PGP_MPI **mpi)
{
    PGP_MPI    *n;
    int            len = (bits + 7) / 8;

    if (bits < 0 || bits > 0xFFFF)
    {
        px_debug("pgp_mpi_alloc: unreasonable request: bits=%d", bits);
        return PXE_PGP_CORRUPT_DATA;
    }
    n = crypt_alloc(sizeof(*n) + len);
    n->bits = bits;
    n->bytes = len;
    n->data = (uint8 *) (n) + sizeof(*n);
    *mpi = n;
    return 0;
}

int
pgp_mpi_create(uint8 *data, int bits, PGP_MPI **mpi)
{
    int            res;
    PGP_MPI    *n;

    res = pgp_mpi_alloc(bits, &n);
    if (res < 0)
        return res;
    memcpy(n->data, data, n->bytes);
    *mpi = n;
    return 0;
}

int
pgp_mpi_free(PGP_MPI *mpi)
{
    if (mpi == NULL)
        return 0;
    crypt_memset(mpi, 0, sizeof(*mpi) + mpi->bytes);
    crypt_free(mpi);
    return 0;
}

int
pgp_mpi_read(PullFilter *src, PGP_MPI **mpi)
{
    int            res;
    uint8        hdr[2];
    int            bits;
    PGP_MPI    *n;

    res = pullf_read_fixed(src, 2, hdr);
    if (res < 0)
        return res;
    bits = ((unsigned) hdr[0] << 8) + hdr[1];

    res = pgp_mpi_alloc(bits, &n);
    if (res < 0)
        return res;

    res = pullf_read_fixed(src, n->bytes, n->data);
    if (res < 0)
        pgp_mpi_free(n);
    else
        *mpi = n;
    return res;
}

int
pgp_mpi_write(PushFilter *dst, PGP_MPI *n)
{
    int            res;
    uint8        buf[2];

    buf[0] = n->bits >> 8;
    buf[1] = n->bits & 0xFF;
    res = pushf_write(dst, buf, 2);
    if (res >= 0)
        res = pushf_write(dst, n->data, n->bytes);
    return res;
}

int
pgp_mpi_hash(PX_MD *md, PGP_MPI *n)
{
    uint8        buf[2];

    buf[0] = n->bits >> 8;
    buf[1] = n->bits & 0xFF;
    px_md_update(md, buf, 2);
    px_md_update(md, n->data, n->bytes);

    return 0;
}

unsigned
pgp_mpi_cksum(unsigned cksum, PGP_MPI *n)
{
    int            i;

    cksum += n->bits >> 8;
    cksum += n->bits & 0xFF;
    for (i = 0; i < n->bytes; i++)
        cksum += n->data[i];

    return cksum & 0xFFFF;
}
